To make the crust, combine the coconut, cashews, and salt in a food processor and process to fine powder. Add the agave syrup and process to mix well.

To make the tartlet shells, line 4 small tartlet or brioche cups with plastic wrap. Scoop about 2 tablespoons of the crust into each. Using your fingertips, firmly press the crust into the tartlet cup, leaving a cavity in the center to hold the sorbet. Place in the freezer to firm up for at least 30 minutes or more.

To make the mango sorbet, combine the mangoes, water, and agave syrup in a high-speed blender and blend until smooth. Serve immediately. Or, for an icier, more solid texture, scoop into a container and place in the freezer for an hour or more.

To make the mango sorbet in an ice cream maker: Chill the mixture in the freezer for an hour or so, then scoop into the ice cream maker and follow the manufacturer’s instructions.